What was the impact of industrialization on the United States from the 1870s to 1940?
One of the most noticeable and important impacts was a massive migration from the farm to the cities as better paying jobs were available for more and more people as mass production facilities were expanded and farm production became less labor-intensive as machinery came into heavy use on the farm. This shift in population led to political changes in cities and new problems with infrastructure and massive new construction in order to house all the new migrants to the city.
This in turn led to incredibly concentrations of wealth in the hands of the men and corporations that controlled railroads and other important pieces of the industrial process. The growth of speculation and investment led to some of the first large-scale investment bubbles which also led to the Great Depression of the 1930s.